Stained glass block of 9" would be okay! Just pick a simple design rather than one with a lot of details. It would work well.
Reverse applique might work well, too, if you pick a simple design. Perhaps a flower. If you use machine applique, and (water soluble) glue the pieces in prior to sewing them, you can accomplish this with less headache. (When the piece is washed after quilting, the glue dissolves.)